EoW January 2012

Technical article

The measurement technology includes a rapid sample rate that allows data to be captured at a rate of several samples per lay length. This rapid sample rate allows the further processing of the data, such as FFT analysis, trend analysis, and statistical evaluation. 2.1 Pair lay studies Initial trials were set up to measure pair lays that used a rewind line. This arrangement provided a simpler setup and allowed the measurement of pair lays across a number of twinning machines. Analysis and experiments were conducted to evaluate the measurement equipment performance as well as the differences seen across lay set points and process equipment. 2.1.1 Nominal lay of individual pairs An example of the distribution of measured pair lay is shown in Figure 1 . The data is in histogram format, with a probability density that reflects the distribution of the lay length data over the length of the pair sample. The x-axis scale has been calculated as a per cent deviation from the target to normalise the variation and the mean for all comparisons in this study. The overall lay lengths measured fall in to a rather tight band. The variation is on the order of 1% or less, and the mode of the distribution can be determined with somewhat additional precision. 2.1.2 Individual Pair Measurements In one experiment, a single twinning machine was set to a number of process set points, but the lay length set point was unchanged. A series of pairs were made with no two set points in immediate succession, and the samples were made in replicate. Figure 2 shows the comparison of the same lay set points measured at two different times from the same twinner, but with all other machine set points identical. This result shows high repeatability of both the twinner and the measuring technology when pairs with the same twinner, lay set point and process conditions are measured.

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▲ ▲ Figure 2 : Repeated measurements of replicated trials

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▼ ▼ Figure 4 : Same lay length produced on two different machines

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▲ ▲ Figure 3 : Different process set points for the same lay length

2 Experimentation This paper is the outcome of a joint effort of Beta LaserMike and Tyco Electronics to better understand how to measure lay lengths, and correlate those measured values to finished cable performance. In order to develop a better understanding of the measurement capabilities, initial trials on individual pairs were conducted. After the pair lay information was gathered, data was gathered at a cabling line with simultaneous data on multiple pairs.

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EuroWire – January 2012